VERS CALIFORNIA BREEDING YEARLING REEF HEIFERS Reuben Albaugh Horace T. Strong (Revised by Reuben Albaugh) I ^'#lf*iti #*€ CALIFORNIA AGRICULTURAL Experiment Station Px tension Service CIRCULAR 433 REVISED CAECAG 433 1-24 (1972) THIS CIRCULAR points out the economic importance to the cattle industry of breeding heifers at a young age, and of improving the environ- ment of these animals following weaning and again after the first calf is born. It describes how production of beef can be expanded without increasing mature breeding cattle numbers and stresses the man- agement necessary so heifers can be bred at fifteen months of age and produce again at the age of three years. AUGUST, 1972 THE AUTHOR: Reuben Albaugh is Agriculturist, Emeritus, Agricultural Exten- sion, Davis. THE COVER PHOTO shows a group of Shorthorn-Hereford crossbred yearling heifers of breed- ing age. (Biggs Ranch, Butte County; photo courtesy of A. W. Mitchell.) THE PHOTO BELOW shows a group of high-quality, well-grown-out, two-year-old heifers and their calves. [2 BREEDING YEARLING BEEF HEIFERS INCREASING BEEF SUPPLIES USDA reports that, in 1970, 29 million beef calves were produced; one half (14.5 million) were heifers. If 20 per cent, or 2,900,000 of these heifers, could be bred so that they would calve at two years of age, and if heifers would wean a 70 per- cent calf crop, an additional 2,030,000 calves could be produced annually. If these 2,030,000 calves could be fed out and slaughtered at an average weight of 900 pounds and a dressing percentage of 60, they would produce 1,096,200,000 pounds of dressed beef. At the consump- tion rate of 110 pounds per capita, this young heifer breeding program would supply sufficient beef for 9,965,454 people. At weaning these calves should average 400 pounds in weight and sell for 35c per pound at current prices or a gross total of $140 per head. Extra feed, labor and death loss calculated at $25 per heifer bred would leave a net income to the owner who bred yearling heifers of $115 over the producer who breeds heifers to calve at three years of age. Kottman (1971) estimated that simply maintaining the present per-capita con- sumption of 110 pounds of beef will re- quire 8.1 million head more cows by 1985 to meet this demand. This amount of extra beef will be necessary because of increased population growth. One way of meeting this demand without increas- ing numbers of cattle is to feed market animals to a heavier weight. However, several studies have shown that heavier carcasses may carry more excess fat and the cost of producing beef at heavier weights will increase. This is because heavier and older animals require more feed to maintain their body weight. In 1967, according to the USDA, 2.4 billion pounds of fat were trimmed from beef carcasses. This cost the industry 1.5 million dollars in labor, transportation, and feed. A more practical method of supplying the extra beef that will be needed in the future is to breed heifers that will calve at two rather than three years of age. This practice will not in- [3] crease numbers of mature breeding cows and at the same time would enhance the efficiency and income of the cattle in- dustry. The data presented here are based on 2,545 heifers on 15 California ranches, and on experimental results from several research stations on breeding yearling beef heifers. They demonstrate that: Meat production can be increased with- out increasing the number of ma- ture breeding cattle. Greater economic returns are possible on ranches practicing the yearling breeding method. With proper feed, care, and manage- ment, and by weaning the calf be- tween 4-6 months, the heifer's growth and development are not stunted; nor is the percentage of calf crop reduced at three years of age. Breeding heifers to calve early in the year (October, November, and De- cember) for most of the state may reduce mortality of heifers at calving time and decrease difficulty in calv- ing. Among the reasons for these advantages are weather, the physio- logical state of the heifer, or size of calf. In the mountain counties calv- ing should occur in February and March. Breeding yearling heifers to young, and hence light-weight, small-bodied, small-boned bulls of another breed may result in smaller calves at birth, less difficulty at calving time and a higher percentage of calf crop. Cross- bred calves can stand more stress at birth. Use of bulls from large-frame, high-growth-rate breeds is not rec- ommended. Data are limited on breeding yearling heifers of the newer exotic breeds and on the use of exotic bulls with heifers of the British breeds. Until more data are available, guidelines presented in this circular may be fol- lowed with the newer, larger cattle. TO GET BEST RESULTS • Breed only thrifty, high-grading, fast- gaining heifers weighing 600 pounds or more at breeding time and exhibit- ing ample femininity. • Feed for continuous growth — to gain about 1 pound per day. • Provide special care at calving time. • Use young, small-bodied, small- boned bulls. • Crossbreed where possible. TESTS SHOW ADVANTAGES OF EARLY BREEDING Because the prices cattlemen receive for their products are low compared to what they have to pay for goods and service, few producers can afford to delay the breeding of heifers so they calve first at three years of age. With successful man- agement, breeding at yearling age (15 mos) shows great promise for increasing meat supplies and improving ranch pro- duction efficiency without enlarging the numbers of mature breeding animals. Research at several experiment stations documents this statement. Oklahoma studies (Zimmerman, et al. 1958) showed that at 9.5 years of age, cows that calved at two produced 1.15 more calves than those bred to calve at three. Withycombe et al. (1930) in Oregon indicated that at the end of six years cows calving at two had produced 7/10's more than those first calving at three. Utah experiments (Bennett, et al. 1949) demonstrated that heifers bred as vearlings, at the end of 10 years, had produced 1.03 more calves than their herd mates that were bred to calve at three. Pinney et al. (1971) proved that, in Oklahoma at the end of 11/2 years heifers that had been bred to calve first at two had produced nearly one more calf or about 338.8 pounds of calf weight. Three main problems are connected with calving out two-year-old heifers: 1) The heifers must be managed so that they will come into sexual maturity at 12-13 [4] TABLE 1. FEED EFFECTS ON HEIFER REPRODUCTION Data Winter grain group Number of head Winter gain (lb/day) Feed required (lb/day)* Hay Graint Summer gain (lb/day) Body weight (lb) At end of winter (5/6) Start of Breeding (6/15) . . . October, 15 Puberty age (days) Percentage in heat: Prior to breeding season .... During breeding season .... After breeding season Percentage bred and conceived: First 20 days Second 20 days Third 20 days Not bred October pregnancy (per cent) . 30 0.6 10.2 1.3 414 458 629 434 7 73 20 30 10 10 20 50 29 1.0 10.6 1.9 1.2 481 527 667 412 31 66 3 62 21 3 3 86 30 1.5 11.4 4.4 0.9 558 584 708 388 83 17 0 60 20 7 0 87 * Calculated on weighted average basis. t Ground grain mix: 70 per cent barley; 12.5 per cent linseed meal, 12.5 per c«nt wheat bran and 5 per cent molasses. months of age, conceive, and calve early in the breeding season; 2) they must have the proper environment during the lacta- tion period of their first calving; and 3) must be fed during the first gestation period so that they will calve easily. Bergland (1959), working with 222 first-calf Hereford heifers in Montana, re- lated the first calving date of the heifer to her lifetime production. He found that • Heifers that produced a calf early in the calving season as a heifer con- tinued to calve earlv and wean heav- ier calves throughout their lifetime. • The later the calving date as a two- year-old, the higher the probability of the cow being open later in life. • Heifers that produced the first calf late in the calving season had a more erratic lifetime reproductive per- formance. The most common pattern in the erratic production was calf production in alternate years. Bellows (1971) conducted an experi- ment using 89 crossbred Angus-Hereford and Hereford-Angus yearling heifers. He fed these animals in three groups during the first winter after weaning so their daily gain would be 6/10 pound, 1 pound, and 1/2 pounds, respectively. They were fed from December 5 to May 6, a period of 152 days. The following summer they were grazed together on native range. Table 1 summaries the results of this test. At the end of the grazing season, heif- ers fed the high ration averaged 79 lbs more in weight than those fed the lower one. Some 27 per cent of the heifers that wintered at a low rate of gain failed to come into heat during the breeding sea- son, reducing the calf crop 20 per cent, compared to 97 and 100 per cent maxi- mum for the groups two and three. In October all heifers were checked for pregnancy. Group one, the low-gaining lot, had 36-37 per cent less pregnancies than groups two and three. This alone points out the importance of adequate nutrition during the first winter period after weaning. Young heifers to be bred at 15 months of age after weaning should be [5] fed so they will gain approximately a pound a day during this period. Bellows (1971) also conducted experi- ments using 62 head of crossbred Here- ford-Angus yearlings. This experiment studied the effects of nutrition on the birth weights of calves, a controversial subject. All heifers in this group were bred arti- ficially to a single Angus sire. Ninety days before calving the heifers were placed in a feedlot and fed a high- and low-level ration. Studied were cow weight changes, calf birth weights and calving difficulty. After calving, these heifers were held in the feedlot and fed good quality alfalfa hay plus 7/2 pounds of grain per head per day. The grain ration consisted of 70 per cent barley, 12.5 per cent linseed oil meal, 12.5 per cent wheat bran and 5 per cent molasses. All heifers were grazed together during the remainder of the study. The percentage of heifers requiring assistance during calving was identical for both groups. This information agrees with the data being assembled at Ne- braska and Colorado. The calves from the group fed at a high level weighed 14 pounds more at weaning time than those from heifers on the low plane of nutrition. Only 68 per cent of the low-fed group came into heat for their second calving while 97 per cent of the high group showed estrus early in the breeding sea- son. Table 2 summarizes these data. To summarize these tests: Weaner heifer calves can be conditioned to be high- or low-time producers simply by manipulat- ing the plane of nutrition during the first winter following weaning. Further re- sults point out that feeding pregnant yearling heifers poorly from weaning to calving is false economy. TABLE 2. EFFECTS OF GESTATION FEED LEVEL ON CALVING DIFFICULTY AND HEIFER REPRODUCTION Data Feed level last 90 days of gestation Number of head Feed level (lb/day) Hay Grain Heifer gain (lb /day) Cow weight (lb) Initial Precalving 24-hour postcalving Calf data: Birth weight (lb)* Calving diff. (per cent) Average scoret Weight 6/12 (lb) (about 2 months old) Weaning weight (lb) Cow data :% Weight on 4/29 (lb) Weight on 6/12 (lb) Weight at calf weaning (lb) Cow in heat for second calving before breeding season (per cent) * Average of actual birthweights. t Scoring: 1 - no difficulty to 4 = extreme difficulty, including caesarean section. t Cows in feedlots on estimated 16.1 lb TDN from calving to adequate range forage. [6] SEVEN RULES TO FOLLOW Cattlemen who are successful in calv- ing their heifers at two years of age rather than three consider proper feed and care very important. Data collected at several experiment stations and on 15 California ranches involving 2,545 heif- ers indicate that Success for this early breeding program requires the rigid observation of the seven rules listed here: 1 — Breed only thrifty, fast-gaining, high- grading heifers that weigh 600 pounds or more at breeding time, have large pelvic openings, and exhibit a high degree of femininity. Use crossbred heifers. They come into sexual maturity early, tend to have larger pelvic openings, have a high conception rate, and exhibit less trouble at calving time. Table 3 documents this statement. Bellows, et al. (1971) extensively studied calving difficulties among two-year-old heifers, using 95 Herefords and 103 Angus heifers. The Hereford heifers were bred artificially to an Augus bull and the Angus heifers to a Hereford bull. Calves resulting from this mating were all cross- breds. In this test Bellows compared 14 vari- ables that were related to calving diffi- culties. For the cow, they were: body- weight at the end of the breeding season, mid-gestation and just prior to calving; weight gains during these three periods; precalving measurements of fat thickness, precondition score, and precalving pelvic height, width and area. For the calf, the difficulties were: ges- tation length, sex, and birth weight. Factors that contributed to most of the calving difficulties were pre-calving weight of the dam, pelvic area, sex of calf, and birth weight of the calf. Factors that contributed most to the birth weight of the calf were: pre-calving weight of the dam, gestation length, and sex of calf. In other words, big cows tend to have less trouble calving than smaller ones, even though their calves were heavier at birth. Bull calves were heavier at birth and con- sequently caused more difficulty at calv- ing time. Cows with larger pelvic open- ings had less calving difficulties than those that were smaller. Longer gestation resulted in larger calves at birth. Experiments are being conducted in which pelvic openings of young heifers prior to breeding are measured. If the results of these studies indicate heifers with larger pelvic openings at this young age have less calving difficulties, this will be another measuring stick for culling and selecting replacement breeding heifers. TABLE 3. STRAIGHTBRED AND CROSSBRED HEIFERS COMPARED Breed group Number Age Weight Pelvic area Straightbred: Angus 14 16 23 34 39 28 5 7 9 days 360 386 370 368 370 374 330 344 333 pounds 588 596 700 585 649 648 631 638 674 sq. cm. 153.0 Hereford 157.2 Charolais 189.0 Crossbred:* AXH 159.3 AXC 174.0 HXC 176.8 A X BS 168.8 H X BS 171.6 C X BS 176.2 * A = Angus; H = Hereford; C Source: Bellows (1971). Charolais; BS = Brown Swiss. [7] Above: Young small-bodied and small-boned Hereford bull, a good type to breed to yearling heifers. Calves from this mating should not be kept for breeding but should be sold for beef. Below: A good type Angus bull for breeding to young heifers. m 2 — Keep heifers in thrifty growing condi- tion by supplementary feeding during the short dry-grass season. In California it is a good nutritional plan to feed the heifer for continuous growth after she is weaned and until she is approximately two and one half years old. On most ranches, these large heifers are selected at weaning time and then supplemented on the range with approx- imately 1 to 1/2 pounds of cottonseed cake per head per day until the range grass will furnish adequate nutrients for good gains. Heifers fed on the range in this manner should gain from % to 1 pound per head per day, which is sufficient for breeding animals. In the mountain areas, where heifers are wintered in the feedyard, a couple of pounds of concentrates per head per day plus good legume or mixed legume hay, fed free choice, will provide adequate gains. In the early fall, after the heifers have been bred as yearlings, supplement them on the range with cottonseed cake or some other high-protein feed until the grass is again adequate to keep them supplied with proper nutrients. On some ranches where permanent irrigated pas- ture is available, the only supplementary feed necessary is some roughage, such as hay, to prevent bloat and scouring. Under feedlot conditions in the north- ern counties, supplying these heifers with 20-25 pounds of good-quality alfalfa or mixed legume hav will give them the proper plane of nutrition for adequate growth. Two-year-old heifers, at the time they wean their first calves should weigh about 800 pounds. After calving, a two-year-old cow will require 28 pounds of feed containing 1.4 pounds protein, 16.18 pounds TDN, 30 grams calcium, 23 grams phosphorus, 14 grams magnesium, and 42,000 I.U. vita- min A. A ration that will meet these re- quirements is 28 pounds alfalfa hay or 30 pounds of mixed legume hay. 3 — Breed heifers to small-bodied, small- boned, young bulls. Small-bodied, small-boned bulls tend to sire calves that are small at birth. This is important in this early breeding pro- gram because it prevents losses of both calves and heifers and saves time and labor. Young bulls are recommended, not because they usually sire calves which are lighter in weight, but because these young bulls are small, and are not apt to injure the heifers at breeding time. Keep and use bulls which continue to sire calves that are small yet thrifty and vigorous at birth as long as possible, re- gardless of age, type, or breed. Some cattlemen who practice this early breeding method use small-bodied, small- boned Angus bulls on Hereford heifers, because they believe the calf resulting from this cross is smaller at birth, is more vigorous, and produces a more efficient feeder animal. In 1942, 46 Hereford heifers on one ranch in Monterey County were bred to two Angus bulls. Forty-two crossbred calves were raised and sold for veal. They were popular with the packer and brought top prices. No losses of cows or calves occurred. Other breeds producing small calves at birth are the Texas Longhorn and the Jersey. Work at the Ohio Experiment Station (table 4) indicated that the gestation period of Aberdeen-Angus cows is about ten days shorter than that of Hereford cows. This shorter gestation period may have some bearing on the theory that the crossbred Angus-Hereford calf is smaller at birth. In this test, 101 gestation periods for purebred Angus calves averaged 276.47 days; for 100 purebred Hereford calves, 286.28 days; for 94 crossbred Hereford- Angus calves. 281.98 days; for 102 cross- bred Angus-Hereford calves 283.30 days. The Oaklahoma Station at Stillwater, Oklahoma, established a test to compare Augus bulls on Hereford heifers to Here- ford bulls on Hereford heifers. Twenty- three Hereford heifers, averaging 474 pounds at 441 days of age, were placed in a pasture with an Angus bull. A similar number of heifers of the same weight and age were placed in a pasture with a Here- ford bull. Both bulls were classed as medium-to-small in size and were consid- ered comparable in that respect. The [9 A two-year-old Angus bull and yearling heifer. results of the test are presented in table 5. A study of these data reveals that • Crossbred calves were calved about five days earlier than the straight Hereford calves. • The crossbred calves were 6 pounds lighter at birth. • A larger number of crossbred calves were weaned. • At weaning time, crossbred calves were 17 pounds heavier. • A larger number of the cows raising crossbred calves were pregnant at weaning time, although all cows had been exposed to the same bulls for the same period of time. One cattleman in Monterey County bred yearling Hereford heifers to a Brah- man bull with fair results. This project, carried on for two years, showed that the calves were smaller at birth than straight Herefords, and little trouble was experi- enced at calving time. The average birth weight of a representative group of cross- bred Brahman-Hereford calves was 62 pounds. These calves made excellent veal and were popular with the packer. They brought a higher price per pound than did straight Hereford calves of similar age. The test included 71 heifers, and a 49.3 per cent calf crop was sold. This low calf crop may have been due to low rain- fall causing short feed conditions. 4 — Wean calves from the two-year-old heifers between 4 and 6 months. When the calf is weaned at this age, the cow has a chance to grow and de- velop. Weaning these calves early may help prevent the occurrence of nonbreed- ers and insures a large calf crop when the heifers are three years of age. In areas of adequate feed supply heifers not bred until two years of age may become too fat. This could impair their productive performance bv reducing milk supply and causing difficult calving. Observations on one ranch in Monte- rey County showed that the percentage of calf crop from three-year-old heifers was 10 per cent higher on heifers that calved at two years than on those that calved for the first time as three-year- olds. The 12-years average percentage of calf crop on this ranch for mature cows was 89.64 per cent. The observations covered about 500 breeding cows per year. Had [10] z o < - < < Ul >- I -I m to CO OS 8 g o 0 W N^l« r-i r-i S © 00 to OS tH CN CO N n © •3 a < u ^ ^ op oo * w w ^ ^ § CN a © us OS fc W 00 N N "*? q Ul TJtJ * ©Ti w n n a» tH t-i o £•8 CO (O CO H o ©• CN CO CN •d *S o si} V # CO ^ H H tH IO U) IT) W IO IO CN 8 a o •h CO O ■o| t-j q ■<* to to tH N-l a> © co i> cn* co" tH r-i CO £ © oo to CO " tH t-i 4) 00 tO t» CN "3 CN ^ CN O °«2 fi| # CN CN O O o CO M 0 a s n U) IT) IO IO IO CN o CN CN "^ CN C- 00 q •^ © 05 t> CN tO* T|i t-i t-i c* to 00 CO CN ^ CN * co co os os os 00 * U) IO ^ ^ ■^ tH A ' • m ■e ; o. t^ >» T3 IS • CI o d 13 o n c3 T3 .o. +2 "9 5 '•3 •£ O — • XI be bo "\ bo £s c3 P •c M.SP.S >. bB >» 2 t5 8 a •3 •§ ■a *» 5? rt .a O 0. '•8 * r< * £> * 1-4 r> < n > £ c * [11] TABLE 5 — SUMMARY OF THE CALVING PERFORMANCE OF TWO-YEAR- OLD HEREFORD HEIFERS BRED TO HEREFORD AND ANGUS BULLS AT STILLWATER, OKLAHOMA* Hereford Bull Angus Bull Number of cows bred to each bull 23 23 Sex of calf Male Female Male Female Number of calves born 9 64 2 2 1 7 April 13 331 800 5 11 63 4 1 1 10 April 2 314 824 7 14 60 5 0 0 14 April 6 338 808 11 8 Average birth weight (lb.) 55 Number of calves pulled 0 Number of calves lost at calving . 0 Number of cows lost at calving 0 Number of calves weaned 8 Average birth date of calves March 26 Average weaning weight of calves (10-4-51) 339 Average weight of cows raising calves Number of cows found pregnant (10-4-51) 882 8 * This work was conducted at the Oklahoma A. & M. Experiment Station, Stillwater, Oklahoma, by Doyle Chambers, Associate Professor of Animal Husbandry, and J. A. Whatley, Jr., Associate Professor of Animal Husbandry. the breeding of the yearling heifers inter- fered with their ability to conceive as two- year-olds, this percentage of calf crop would have been materially lower. These heifers were about 27 months of age when their first calves were weaned. Their average weight was 803 pounds at that time, indicating that breeding them as yearlings did not stunt their growth nor retard their future production. These excellent yearling heifers averaged 671 pounds when bred to a Brahman bul [12 rH t* CO oo ffi co oq in OHNW tH CM tH tJH lO lO 00 CM CO iri t> t> m Oi 0000 >f I>05lOrH tK I HH CO -^ rtf o tH 00 Ci CM C0 03CDO ■* I HH CM CO o 00 o 00 T-l CO 00 00 CO co CO l> t> co CO it 5« m co co »h o co t»oooo tJH rH rH rH in CO CD Oi OS o in lO CO CD I> OS <* m CM t> ITS O) CD ^ CM tH CD r*< CO CO «tf CM m t> 00 00 tK 00 CO t* CO 55 t/> I- ^ tt m CO H00HCO tH tH t> © 00 CO Tfl iH tH tH in CO CD S l> t> CO tH CO th in m -^ u)Q < t? - CO ■* I HH CO iH -# tH O G5 "J CD O r* r| t> oo m m ^ CM m cm co • & °° £ 0 fe ri S f bO ^ . ^-h > ! »H .3 0 co w B CO 0 •iH ;-. 0) ft w "el's -p (-1 cu S* ft o ° 2 ° co R!g M cu CO -a d ce cu bD CU J-t CO O ^ u _] ^ o 'd CO «« cu ^^ cu cu « t g bO ^ s^ g § bo 1 » ^; s ^ *2 3 SSI « cu o^ ^ S bo bO+i +» «m > > o < < En co o ft ^ [13] Zimmerman et at. (1958) compared the lifetime performance of heifers bred to calve at two years of age to those that calved first at three years and were fed different levels of winter feeding. Table 6 gives the results of this 9% year study. These results show that age of breeding or amount of supplementary feeding did not alter the final mature weights of these animals. Cows at the Union Station in Oregon that had calved as two-year-olds pro- duced a 79.6 per cent calf crop at three years of age. At four years, the per- centage of calf crop was 86.1, at five years 94.7, and at six years 83.3. Many authorities believe that milk production is the principal stress limiting growth in these young heifers, and there- fore it is strongly recommended that they receive proper nutrition and care until the second calf is weaned. Under drought- like conditions, calves on two-year-old heifers can be creep-fed or sold as veal at about three months of age. Evidence accumulated by S. W. Mead at the Uni- versity of California Experiment Station, Davis, shows that weaning the calf at three months has no retarding effect on the future milk production of the cow. The following paragraph taken from Roscoe R. Snapp's book Beef Cattle may help to explain this theory: "There is much evidence that gestation has a less stunting effect upon immature heifers than has lactation. This statement seems reasonable in view of the fact that the new-born calf contains only about 15 pounds of protein and 3 pounds of fat, whereas about 65 pounds of protein, 70 pounds of fat, and 90 pounds of carbo- hydrates are in the milk produced by the young mother during the first 4 months of lactation." 5 — Give special care and attention to the heifers at calving time. When young heifers are ready to calve, place them in small fields equipped with corrals and other facilities for restraining and handling cases of difficult calving. Have an experienced person watch them closely. Drive any heifer having difficulty slowly and carefully into one of these small corrals, where assistance can be given. The calf -puller (see photo) is a valuable piece of equipment for anyone employ- ing this early breeding program. Use the calf-puller carefully and intelligently. Nasco-West in Modesto, California, is one company carrying this product. Work conducted by Bellows (1971) in- dicated that out of 6,409 carvings, 380 calves died — 75 per cent of this death loss occurred at birth. In this 10-year study the cows calved on the open range for the first six years, and calf loss was 9.5 per cent in first-calf heifers. 4.3 per cent in 4-year-olds; and 2.4 per cent in cows 5 years or older. During the last four years of this test, cows were managed in small enclosures and 2-3-year-old heifers were watched closely during calving sea- son. Losses dropped to 6.4 per cent in 3- year-old heifers and 4.3 per cent in 2- y ear-olds. Bellows concludes that most calf losses can be prevented if cattlemen make closer observations and give more assistance to cows during calving time. 6 — Breed heifers so that most will calve during September-December (later in the cold, high country). Schoonover (1969) suggests that year- ling heifers be bred from one month to six weeks earlier than the main breeding herd. If this is practiced, future calving dates of diese heifers will be similar to those of the main herd. The reason these young heifers need a longer breeding season is because it will take them longer to recover from the stress of calving than older cows. When the average calving date is de- layed 30 days, it is equivalent to reduc- ing calf crop by 10 per cent which may lower the net profit bv 25 per cent. Put- ting it another way, each time a cow misses a heat period (21 days), it is going to cost the operator about $10 (Pope, 1971). On most California cattle ranches these young heifers are now bred to calve dur- ing September, October, November and December. In the mountain counties where spring calves are desired, February and March are the recommended months. [14] «*,., ,. ^,„. ,/. tf *■»■■*» <»— ^ W|i1|l|'lj Calf puller in operation — a valuable piece of equipment for a cattle ranch. Operator must be sure the calf is in correct position for delivery before applying puller. If in doubt, call a veterinarian. A sixteen-year yearling heifer breeding program on a ranch in Monterey County is summarized in table 7. 7 — Breed only a few heifers the first year of the program to allow operator to gain experience. Results of field tests secured on 15 California ranches (table 8) demonstrated that beef production and economic re- turns can be increased, when beef heifers are bred to calve at two years of age. These data, coming from 2,545 heifers, producing 1,718 calves and including 16 years of records on one ranch, show a total production of 486,194 pounds or 243 tons of meat with a gross return of $108, 420.26. The average return of these heifers as two-year-olds was $59.00 for 15] z u z < UI Z o z o < o o o z 5 CO * £§ X O u |s < Z si < ui >- Z in ui h- >< < Ik O >- a < i ui -4 CO < © o M « '© J3 © Ph © H CO 00 lOtt o t« 09- *H y-4 to 0) a o o « Ph O <0 N CO H 00 t- t« H H IO « O H iH CN CO C* CN CO CN to CI •a « u u © i-i V Ph © ■a > *H to to to *# o cn rl C^ (O ^ (O O) tO n 3 o o « Ph o» tO lO |> 00 CO OJ rH tO CO tH W t- 00 iH rH CN CN CN CN iH CD to © +i 2 ° « CN to o o o o o co i> p p p © 00 OJ lO 00 H W W N H N N « M CO IO oo Average weight calves sold N tJ< 00 G> ^ H 00 CN CO CO tO t> CN tO N N CO N W CO N <5 to CN Per cent calf crop sold w o> OJ H ^ io o 10 cd to oo en oo t> to to 4* « " © ph CO O) CO H CO O) CO CO t* t* ^ ^ CO 00 M © •s "S a o M © Ph rl OJ N CO CO <« 'riN°N° 09 © J* "3 o U) IO U) O) 00 t< 1 t> t- t» t» 00 O) CO 00 1 t> 3 T3 M H H ►* H H H >» fc>> >» t>> >► >> >» ^3 T3 *^3 ^3 *?3 ^0 *T3 »_ i-, t, i_ i_ ■_ >_ o o o o o o o ■M «*H MH «*H «tH «*H «H 4) © 4) V (O 4> CO M M In I-i I-i Ii I-i 0> 0) 0) 0> 0> «D 0) W ffi K ffi W W W © o 0) I 0) ^ Pm ft, fc ft, fc ft* < ©> •OS'S a ©x> t- o> w to tJ< t* CO i> co oo oo oo oo to tO CO iH T-l to © CO t- TT t* V 00 O) Q H N m ^ G» CJ> CD O 1 1 ^ [16] O z 5 CO O 3 - < 3 © 1 • "** .a .5 > 1 *> ^8 n 1 © o "§•« • 00 a» d . fr- t- 3* O M 1 CD tN CO tH IO CO e* CO CO CN Pi © OS CO fr- tH CO o CO ©nu to tH co IO CO IO N ► »S CO CO tH CO CO CO tN < p. ta- © ^> fr- IO CO CO co IO CO io 9 3 3 CD CO 3 3 Per cent calf crop sold oo 00 co tH co O fr- 00 fr- CO fr- oo fr- ee ^"S» ©"O CO CJ> o 00 CO *i*|3 CO tH tH IO 3 IO *H •M o ■sf o c* <# C* o O tH 4. SI 0«S 5*3 tH 8 So •a 5? ■s § 11 .2 2 £ n s b| n & 1 3 w5o 5 • d S W •2 S <2S 4 I "Si ► 4 * ■S-l 3 c« © * 1 g 8 o fr- 8 t i ee o 00 s CO s fr- s co t- CO CO IO IO CO IO IO CO s b- IO "pi 3 ©.o CO tH CM o> co CO s %* tH tN © « Is ^ tH CO tH T-l T-l fcS *? *? g tH °? 1 IO 1 tH IO CO 8 s IO 3 o> o> o» o> o> T-l tH tH tH tH iH i < 1 > f 2 o •a i & s> I 1 1 1 M I ii » [17] TABLE 9 — VALUE LOST THROUGH MORTALITY OF HEIFERS County Number heifers bred Per cent died calving Loss per heifer bred* Imperial 136 245 1,925 63 109 67 0 1.2 2.4 3.2 0 0 $ .00 Madera 1.84 Monterey 2.22 Shasta 4.76 Stanislaus Sutter 0 0 Total 2,545 2.1 Average $2.05 * Losses were based on the following valuations per heifer died. 1937-43 $80 per head 1943 90 per head 1944-47 100 per head 1948-52 150 per head each heifer which produced a calf. The majority of these calves were sold be- tween 1943-1947 at an average price of $16.60 per hundredweight. Based on 1971 prices ($40.00/cwt), the average return per heifer would be about $97.20. The average production per heifer bred amounted to 193 pounds, or 247 pounds per heifer calved. The average mortality of heifers at calving time was 2.1 per cent. This amounted to $2.05 loss per heifer bred (table 9). The percentage of calf crop sold averaged 67 per cent. Loss of calves from calving to veal age was 15.6 per cent. The Oregon Experiment Station at Union found that beef cows which first calved at two years were more profitable than those which first calved at three. The difference between the two groups at the end of four years was $36.15 per head. At the end of six and one-half years, the cows that had calved first at two years had produced .7 more calves than those first calving at three. When five years old, the cows that had calved at two years were about 100 pounds lighter than those first calving at three; but they were producing as many calves of an equal size, and so were just as valuable Braford calves raised by two-year-old Hereford heifers. The calves are about 2 months of age. [18 from the breeding standpoint. The pos- sible reason these early bred cows were lighter in weight at the end of five years was because their calves were allowed to nurse until they were from six to seven months of age. The Utah Experiment Station at Logan, Utah, presents the following data regard- ing breeding of range Hereford heifers as yearlings to a Hereford bull: • Calving at two years of age did not stunt range cows that were well fed during the winter. • Conception rate was not high in yearling range heifers, especially in smaller and younger ones. • Heifers calving at two years of age had difficulty in calving. • When both groups were six years of age, cows calving first at two years, weaned an aveage of 1.03 more calves that were 10 pounds heavier than did cows that calved first at three years of age. • In the fall, when both groups were six years old, the early calving group had weaned an average of 1,236 pounds of calf per cow compared to 865 pounds of calf per cow for the group that calved first at three years. The difference of 371 pounds in favor of early breeding was a result of the cows raising an average of 1.03 more calves per cow and the calves averaging 10 pounds more in weight. The workers conducting this study sug- gest that if animals are small, or if the operator cannot give them proper atten- tion during calving, the practice of breed- ing yearling heifers should not be rec- ommended. Ranchers should not breed heifers as yearlings unless adequate feed supplies are available to grow the heifers out to a large size at the time of calving. Below, left. Two-year-old Hereford heifer with three-months-old calf. Photo on right shows cross- bred Angus-Hereford calves from two-year-old heifers (average 243 pounds). Calves from this cross are usually polled and black-bodied with a white or mottled face. [19] SUMMARY These data on breeding yearling beef the heifer when she calves the second time heifers as secured under field conditions (three years of age), and it affords a nat- in California and researched at several ural method of selecting a cow herd of experiment stations have led many goo